Not Applicable.
Not Applicable.
1. Field of the Invention
The present invention relates to a six-stroke internal combustion engine in which all valves in the combustion chamber function as both intake valves in an intake stroke and exhaust valves in an exhaust stroke.
2. Description of the Related Art
Valves functioning as both intake and exhaust valves are conventionally known from U.S. Pat. No. 1,259,728. A valve or valves in a combustion chamber open in an exhaust stroke and remain open in the intake stroke of the next cycle. Therefore, each valve operates as both intake valve and exhaust valve in order to improve engine efficiency.
One of the problems with the above systems is that, because there is no interval between an exhaust stroke and the intake stroke of the next cycle, some of the exhaust gases are drawn into the cylinder in the next intake stroke. This reduces the engine efficiency. There are also moving parts such as sleeve valves in the cylinder head that increase friction and require extra lubrication. Moreover, inlet ports and outlet ports were designed in a manner that, even if there was an interval between an exhaust stroke and the intake stroke of the next cycle, some of the gases of the exhaust stroke would be drawn into the cylinder in the intake stroke of the next cycle.
Various types of six-stroke reciprocating piston internal combustion engines have been heretofore designed and some examples of which are disclosed in U.S. Pat. No. 2,420,136, U.S. Pat. No. 4,289,097, U.S. Pat. No. 4,924,823, FR Patent No. 2,547,625, CN Patent No. 1,412,422, and JP Patent No. 2,119,635.
There are various modes of cycling the intake charge and exhaust gases during the operation of the six-stroke engines to improve energy efficiency. But a six-stroke internal combustion engine with intake-exhaust valves utilizing stroke five and stroke six as an interval between an exhaust stroke and the intake stroke of the next cycle is not known.
In order to increase volumetric efficiency, the area of intake and exhaust valves and ports must be increased so that more air or fuel-air mixture is introduced into a cylinder in an intake stroke, and more exhaust gases are expelled from the cylinder in an exhaust stroke. That is why internal combustion engines with three, four or five valves per cylinder are manufactured. It is to be noted that more than five valves in the combustion chamber of a cylinder will lead to mechanical complexities which make them practically impossible.
The main object of the present invention is to increase the area of intake and exhaust valves and ports in order to generate a large power and torque and to improve engine efficiency. In this invention, all of the valves in the combustion chamber function as both intake valves and exhaust valves; in other words, air or fuel-air mixture goes into a cylinder via all of the combustion chamber valves in an intake stroke and in an exhaust stroke, the exhaust gases are expelled from the cylinder via the same valves. The inlet ports and outlet ports are connected to each other in the cylinder head. Therefore, in this engine the area of the intake and exhaust valves and ports increases by two times in comparison with the area of the intake and exhaust valves and ports in a traditional engine with the same number of valves in the combustion chamber. It should be noted that the name of said combustion chamber valves is intake-exhaust valves or inlet-outlet valves.
Special exhaust valves are mounted in the side of the cylinder head, outside the combustion chamber in the outlet ports. Said exhaust valves are closed in the intake stroke and are open in the exhaust stroke. As a result, exhaust gases are expelled from the cylinder and cylinder head via the outlet ports, and said exhaust gases do not go into the inlet ports in the exhaust stroke. Also, in the intake stroke, exhaust gases of the previous exhaust stroke are not drawn into the cylinder.
There is a need for an interval at the end of the exhaust stroke during which exhaust gases are expelled from the cylinder head completely. There is also a need for a mechanism to close the combustion chamber valves (intake-exhaust valves) at the end of the exhaust stroke and open them at the beginning of the intake stroke of the next cycle within the interval. Therefore, the fifth stroke and the sixth stroke are considered for the engine related to the invention; in other words, this engine operates on a six-stroke cycle.
Special cams are designed for the valves of the engine. The radius and circumference of said cams are fifty percent larger than the radius and circumference of the traditional ones used in a four-stroke engine in order to cover all of the six strokes. In this case, there is no need to change the camshaft-to-crankshaft gear ratio used in a traditional four-stroke engine.
The present invention is applied to gasoline engines, diesel engines, and also multi-cylinder engines.